Chemical products such as cleaning compounds are used extensively in many cleaning processes such as commercial laundering, industrial warewashing and housekeeping. In these applications, a number of laundry or dishwashing machines may require one or more chemical products to be delivered at different points in their wash cycles. Initially, individual dispensers were used to deliver single chemical products to individual machines. Due to cost concerns, however, dispensing systems have been developed for selectively delivering a plurality of chemical products to a plurality of utilization points.
In most dispensing systems of this type, chemical products are supplied in concentrated form, e.g., solid, granulated, powdered, or liquid, and are mixed with a diluent such as water to form use dilutions that are thereafter distributed to particular utilization points. Often, the quantity of chemical product delivered must be carefully controlled to ensure optimum cleaning performance. In addition, different use dilutions may need to be separated from one another to prevent incompatible chemical products from reacting with one another. Segregation of use dilutions is typically performed by delivering discrete quantities of diluent between use dilutions to "flush" any residual use dilutions from the system.
Many conventional designs utilize a mixing apparatus having a mixing manifold with a diluent input coupled to an diluent supply and a plurality of inputs coupled to a plurality of chemical product sources. Diluent mixes with one or more chemical products in the mixing manifold to form a use dilution, and a delivery pump coupled to the output of the manifold delivers the use dilution out of the mixing manifold.
Diluent is typically supplied by line pressure and is controlled via a valve. The chemical products may be supplied by individual pumps, or alternatively, each chemical product source may be coupled to the manifold through a valve, such that operation of the delivery pump simply draws chemical product into the manifold.
The use dilution delivered by the delivery pump is typically distributed to individual utilization points using a diverter manifold having a plurality of outputs with individual control valves for each output. However, the use of a diverter manifold with individual output valves presents several problems.
The use of multiple valves adds cost and complexity to the dispensing system, as well as increases the size of the dispensing system. Moreover, proof-of-delivery (POD) verification is difficult to achieve using a multi-valve diverter manifold.
Should an output valve fail in an open position, subsequent deliveries of use dilution to other utilization points may be diverted in part through the failed valve, resulting in an inadequate supply of use dilution.
On the other hand, should an output valve fail in a closed position, damage to the delivery pump may occur since the diverter manifold may potentially be closed at each output. Often, a separate pressure relief valve is required to protect against this situation.
In either case, direct verification of proof-of-delivery (i.e., that only the selected output valve is open in the diverter manifold) is often not possible. An indirect method of verifying proof-of-delivery, such as using individual sensors to detect flow or product presence (e.g., conductivity sensors, pressure switches, flowmeters) at each output, may instead be required. The use of individual sensors, however, is extremely expensive and adds significant size and complexity to the dispensing system.
Therefore, there is a significant need for a manner of reliably distributing use dilutions to a plurality of utilization points which is less expensive, less complex and smaller than conventional diverter manifolds, and which is capable of providing accurate proof-of-delivery verification.